init/initramfs_test.c - pub/scm/linux/kernel/git/mkl/linux-can-next - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 #include <kunit/test.h>
 #include <linux/fcntl.h>
 #include <linux/file.h>
 #include <linux/fs.h>
 #include <linux/init_syscalls.h>
 #include <linux/stringify.h>
 #include <linux/timekeeping.h>
 #include "initramfs_internal.h"

 struct initramfs_test_cpio {
 	char *magic;
 	unsigned int ino;
 	unsigned int mode;
 	unsigned int uid;
 	unsigned int gid;
 	unsigned int nlink;
 	unsigned int mtime;
 	unsigned int filesize;
 	unsigned int devmajor;
 	unsigned int devminor;
 	unsigned int rdevmajor;
 	unsigned int rdevminor;
 	unsigned int namesize;
 	unsigned int csum;
 	char *fname;
 	char *data;
 };

 static size_t fill_cpio(struct initramfs_test_cpio *cs, size_t csz, char *out)
 {
 	int i;
 	size_t off = 0;

 	for (i = 0; i < csz; i++) {
 		char *pos = &out[off];
 		struct initramfs_test_cpio *c = &cs[i];
 		size_t thislen;

 		/* +1 to account for nulterm */
 		thislen = sprintf(pos, "%s"
 			"%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x"
 			"%s",
 			c->magic, c->ino, c->mode, c->uid, c->gid, c->nlink,
 			c->mtime, c->filesize, c->devmajor, c->devminor,
 			c->rdevmajor, c->rdevminor, c->namesize, c->csum,
 			c->fname) + 1;
 		pr_debug("packing (%zu): %.*s\n", thislen, (int)thislen, pos);
 		off += thislen;
 		while (off & 3)
 			out[off++] = '\0';

 		memcpy(&out[off], c->data, c->filesize);
 		off += c->filesize;
 		while (off & 3)
 			out[off++] = '\0';
 	}

 	return off;
 }

 static void __init initramfs_test_extract(struct kunit *test)
 {
 	char *err, *cpio_srcbuf;
 	size_t len;
 	struct timespec64 ts_before, ts_after;
 	struct kstat st = {};
 	struct initramfs_test_cpio c[] = { {
 		.magic = "070701",
 		.ino = 1,
 		.mode = S_IFREG | 0777,
 		.uid = 12,
 		.gid = 34,
 		.nlink = 1,
 		.mtime = 56,
 		.filesize = 0,
 		.devmajor = 0,
 		.devminor = 1,
 		.rdevmajor = 0,
 		.rdevminor = 0,
 		.namesize = sizeof("initramfs_test_extract"),
 		.csum = 0,
 		.fname = "initramfs_test_extract",
 	}, {
 		.magic = "070701",
 		.ino = 2,
 		.mode = S_IFDIR | 0777,
 		.nlink = 1,
 		.mtime = 57,
 		.devminor = 1,
 		.namesize = sizeof("initramfs_test_extract_dir"),
 		.fname = "initramfs_test_extract_dir",
 	}, {
 		.magic = "070701",
 		.namesize = sizeof("TRAILER!!!"),
 		.fname = "TRAILER!!!",
 	} };

 	/* +3 to cater for any 4-byte end-alignment */
 	cpio_srcbuf = kzalloc(ARRAY_SIZE(c) * (CPIO_HDRLEN + PATH_MAX + 3),
 			      GFP_KERNEL);
 	len = fill_cpio(c, ARRAY_SIZE(c), cpio_srcbuf);

 	ktime_get_real_ts64(&ts_before);
 	err = unpack_to_rootfs(cpio_srcbuf, len);
 	ktime_get_real_ts64(&ts_after);
 	if (err) {
 		KUNIT_FAIL(test, "unpack failed %s", err);
 		goto out;
 	}

 	KUNIT_EXPECT_EQ(test, init_stat(c[0].fname, &st, 0), 0);
 	KUNIT_EXPECT_TRUE(test, S_ISREG(st.mode));
 	KUNIT_EXPECT_TRUE(test, uid_eq(st.uid, KUIDT_INIT(c[0].uid)));
 	KUNIT_EXPECT_TRUE(test, gid_eq(st.gid, KGIDT_INIT(c[0].gid)));
 	KUNIT_EXPECT_EQ(test, st.nlink, 1);
 	if (IS_ENABLED(CONFIG_INITRAMFS_PRESERVE_MTIME)) {
 		KUNIT_EXPECT_EQ(test, st.mtime.tv_sec, c[0].mtime);
 	} else {
 		KUNIT_EXPECT_GE(test, st.mtime.tv_sec, ts_before.tv_sec);
 		KUNIT_EXPECT_LE(test, st.mtime.tv_sec, ts_after.tv_sec);
 	}
 	KUNIT_EXPECT_EQ(test, st.blocks, c[0].filesize);

 	KUNIT_EXPECT_EQ(test, init_stat(c[1].fname, &st, 0), 0);
 	KUNIT_EXPECT_TRUE(test, S_ISDIR(st.mode));
 	if (IS_ENABLED(CONFIG_INITRAMFS_PRESERVE_MTIME)) {
 		KUNIT_EXPECT_EQ(test, st.mtime.tv_sec, c[1].mtime);
 	} else {
 		KUNIT_EXPECT_GE(test, st.mtime.tv_sec, ts_before.tv_sec);
 		KUNIT_EXPECT_LE(test, st.mtime.tv_sec, ts_after.tv_sec);
 	}

 	KUNIT_EXPECT_EQ(test, init_unlink(c[0].fname), 0);
 	KUNIT_EXPECT_EQ(test, init_rmdir(c[1].fname), 0);
 out:
 	kfree(cpio_srcbuf);
 }

 /*
  * Don't terminate filename. Previously, the cpio filename field was passed
  * directly to filp_open(collected, O_CREAT|..) without nulterm checks. See
  * https://lore.kernel.org/linux-fsdevel/20241030035509.20194-2-ddiss@suse.de
  */
 static void __init initramfs_test_fname_overrun(struct kunit *test)
 {
 	char *err, *cpio_srcbuf;
 	size_t len, suffix_off;
 	struct initramfs_test_cpio c[] = { {
 		.magic = "070701",
 		.ino = 1,
 		.mode = S_IFREG | 0777,
 		.uid = 0,
 		.gid = 0,
 		.nlink = 1,
 		.mtime = 1,
 		.filesize = 0,
 		.devmajor = 0,
 		.devminor = 1,
 		.rdevmajor = 0,
 		.rdevminor = 0,
 		.namesize = sizeof("initramfs_test_fname_overrun"),
 		.csum = 0,
 		.fname = "initramfs_test_fname_overrun",
 	} };

 	/*
 	 * poison cpio source buffer, so we can detect overrun. source
 	 * buffer is used by read_into() when hdr or fname
 	 * are already available (e.g. no compression).
 	 */
 	cpio_srcbuf = kmalloc(CPIO_HDRLEN + PATH_MAX + 3, GFP_KERNEL);
 	memset(cpio_srcbuf, 'B', CPIO_HDRLEN + PATH_MAX + 3);
 	/* limit overrun to avoid crashes / filp_open() ENAMETOOLONG */
 	cpio_srcbuf[CPIO_HDRLEN + strlen(c[0].fname) + 20] = '\0';

 	len = fill_cpio(c, ARRAY_SIZE(c), cpio_srcbuf);
 	/* overwrite trailing fname terminator and padding */
 	suffix_off = len - 1;
 	while (cpio_srcbuf[suffix_off] == '\0') {
 		cpio_srcbuf[suffix_off] = 'P';
 		suffix_off--;
 	}

 	err = unpack_to_rootfs(cpio_srcbuf, len);
 	KUNIT_EXPECT_NOT_NULL(test, err);

 	kfree(cpio_srcbuf);
 }

 static void __init initramfs_test_data(struct kunit *test)
 {
 	char *err, *cpio_srcbuf;
 	size_t len;
 	struct file *file;
 	struct initramfs_test_cpio c[] = { {
 		.magic = "070701",
 		.ino = 1,
 		.mode = S_IFREG | 0777,
 		.uid = 0,
 		.gid = 0,
 		.nlink = 1,
 		.mtime = 1,
 		.filesize = sizeof("ASDF") - 1,
 		.devmajor = 0,
 		.devminor = 1,
 		.rdevmajor = 0,
 		.rdevminor = 0,
 		.namesize = sizeof("initramfs_test_data"),
 		.csum = 0,
 		.fname = "initramfs_test_data",
 		.data = "ASDF",
 	} };

 	/* +6 for max name and data 4-byte padding */
 	cpio_srcbuf = kmalloc(CPIO_HDRLEN + c[0].namesize + c[0].filesize + 6,
 			      GFP_KERNEL);

 	len = fill_cpio(c, ARRAY_SIZE(c), cpio_srcbuf);

 	err = unpack_to_rootfs(cpio_srcbuf, len);
 	KUNIT_EXPECT_NULL(test, err);

 	file = filp_open(c[0].fname, O_RDONLY, 0);
 	if (IS_ERR(file)) {
 		KUNIT_FAIL(test, "open failed");
 		goto out;
 	}

 	/* read back file contents into @cpio_srcbuf and confirm match */
 	len = kernel_read(file, cpio_srcbuf, c[0].filesize, NULL);
 	KUNIT_EXPECT_EQ(test, len, c[0].filesize);
 	KUNIT_EXPECT_MEMEQ(test, cpio_srcbuf, c[0].data, len);

 	fput(file);
 	KUNIT_EXPECT_EQ(test, init_unlink(c[0].fname), 0);
 out:
 	kfree(cpio_srcbuf);
 }

 static void __init initramfs_test_csum(struct kunit *test)
 {
 	char *err, *cpio_srcbuf;
 	size_t len;
 	struct initramfs_test_cpio c[] = { {
 		/* 070702 magic indicates a valid csum is present */
 		.magic = "070702",
 		.ino = 1,
 		.mode = S_IFREG | 0777,
 		.nlink = 1,
 		.filesize = sizeof("ASDF") - 1,
 		.devminor = 1,
 		.namesize = sizeof("initramfs_test_csum"),
 		.csum = 'A' + 'S' + 'D' + 'F',
 		.fname = "initramfs_test_csum",
 		.data = "ASDF",
 	}, {
 		/* mix csum entry above with no-csum entry below */
 		.magic = "070701",
 		.ino = 2,
 		.mode = S_IFREG | 0777,
 		.nlink = 1,
 		.filesize = sizeof("ASDF") - 1,
 		.devminor = 1,
 		.namesize = sizeof("initramfs_test_csum_not_here"),
 		/* csum ignored */
 		.csum = 5555,
 		.fname = "initramfs_test_csum_not_here",
 		.data = "ASDF",
 	} };

 	cpio_srcbuf = kmalloc(8192, GFP_KERNEL);

 	len = fill_cpio(c, ARRAY_SIZE(c), cpio_srcbuf);

 	err = unpack_to_rootfs(cpio_srcbuf, len);
 	KUNIT_EXPECT_NULL(test, err);

 	KUNIT_EXPECT_EQ(test, init_unlink(c[0].fname), 0);
 	KUNIT_EXPECT_EQ(test, init_unlink(c[1].fname), 0);

 	/* mess up the csum and confirm that unpack fails */
 	c[0].csum--;
 	len = fill_cpio(c, ARRAY_SIZE(c), cpio_srcbuf);

 	err = unpack_to_rootfs(cpio_srcbuf, len);
 	KUNIT_EXPECT_NOT_NULL(test, err);

 	/*
 	 * file (with content) is still retained in case of bad-csum abort.
 	 * Perhaps we should change this.
 	 */
 	KUNIT_EXPECT_EQ(test, init_unlink(c[0].fname), 0);
 	KUNIT_EXPECT_EQ(test, init_unlink(c[1].fname), -ENOENT);
 	kfree(cpio_srcbuf);
 }

 /*
  * hardlink hashtable may leak when the archive omits a trailer:
  * https://lore.kernel.org/r/20241107002044.16477-10-ddiss@suse.de/
  */
 static void __init initramfs_test_hardlink(struct kunit *test)
 {
 	char *err, *cpio_srcbuf;
 	size_t len;
 	struct kstat st0, st1;
 	struct initramfs_test_cpio c[] = { {
 		.magic = "070701",
 		.ino = 1,
 		.mode = S_IFREG | 0777,
 		.nlink = 2,
 		.devminor = 1,
 		.namesize = sizeof("initramfs_test_hardlink"),
 		.fname = "initramfs_test_hardlink",
 	}, {
 		/* hardlink data is present in last archive entry */
 		.magic = "070701",
 		.ino = 1,
 		.mode = S_IFREG | 0777,
 		.nlink = 2,
 		.filesize = sizeof("ASDF") - 1,
 		.devminor = 1,
 		.namesize = sizeof("initramfs_test_hardlink_link"),
 		.fname = "initramfs_test_hardlink_link",
 		.data = "ASDF",
 	} };

 	cpio_srcbuf = kmalloc(8192, GFP_KERNEL);

 	len = fill_cpio(c, ARRAY_SIZE(c), cpio_srcbuf);

 	err = unpack_to_rootfs(cpio_srcbuf, len);
 	KUNIT_EXPECT_NULL(test, err);

 	KUNIT_EXPECT_EQ(test, init_stat(c[0].fname, &st0, 0), 0);
 	KUNIT_EXPECT_EQ(test, init_stat(c[1].fname, &st1, 0), 0);
 	KUNIT_EXPECT_EQ(test, st0.ino, st1.ino);
 	KUNIT_EXPECT_EQ(test, st0.nlink, 2);
 	KUNIT_EXPECT_EQ(test, st1.nlink, 2);

 	KUNIT_EXPECT_EQ(test, init_unlink(c[0].fname), 0);
 	KUNIT_EXPECT_EQ(test, init_unlink(c[1].fname), 0);

 	kfree(cpio_srcbuf);
 }

 #define INITRAMFS_TEST_MANY_LIMIT 1000
 #define INITRAMFS_TEST_MANY_PATH_MAX (sizeof("initramfs_test_many-") \
 			+ sizeof(__stringify(INITRAMFS_TEST_MANY_LIMIT)))
 static void __init initramfs_test_many(struct kunit *test)
 {
 	char *err, *cpio_srcbuf, *p;
 	size_t len = INITRAMFS_TEST_MANY_LIMIT *
 		     (CPIO_HDRLEN + INITRAMFS_TEST_MANY_PATH_MAX + 3);
 	char thispath[INITRAMFS_TEST_MANY_PATH_MAX];
 	int i;

 	p = cpio_srcbuf = kmalloc(len, GFP_KERNEL);

 	for (i = 0; i < INITRAMFS_TEST_MANY_LIMIT; i++) {
 		struct initramfs_test_cpio c = {
 			.magic = "070701",
 			.ino = i,
 			.mode = S_IFREG | 0777,
 			.nlink = 1,
 			.devminor = 1,
 			.fname = thispath,
 		};

 		c.namesize = 1 + sprintf(thispath, "initramfs_test_many-%d", i);
 		p += fill_cpio(&c, 1, p);
 	}

 	len = p - cpio_srcbuf;
 	err = unpack_to_rootfs(cpio_srcbuf, len);
 	KUNIT_EXPECT_NULL(test, err);

 	for (i = 0; i < INITRAMFS_TEST_MANY_LIMIT; i++) {
 		sprintf(thispath, "initramfs_test_many-%d", i);
 		KUNIT_EXPECT_EQ(test, init_unlink(thispath), 0);
 	}

 	kfree(cpio_srcbuf);
 }

 /*
  * The kunit_case/_suite struct cannot be marked as __initdata as this will be
  * used in debugfs to retrieve results after test has run.
  */
 static struct kunit_case __refdata initramfs_test_cases[] = {
 	KUNIT_CASE(initramfs_test_extract),
 	KUNIT_CASE(initramfs_test_fname_overrun),
 	KUNIT_CASE(initramfs_test_data),
 	KUNIT_CASE(initramfs_test_csum),
 	KUNIT_CASE(initramfs_test_hardlink),
 	KUNIT_CASE(initramfs_test_many),
 	{},
 };

 static struct kunit_suite initramfs_test_suite = {
 	.name = "initramfs",
 	.test_cases = initramfs_test_cases,
 };
 kunit_test_init_section_suites(&initramfs_test_suite);

 MODULE_DESCRIPTION("Initramfs KUnit test suite");
 MODULE_LICENSE("GPL v2");
	// SPDX-License-Identifier: GPL-2.0
	#include <kunit/test.h>
	#include <linux/fcntl.h>
	#include <linux/file.h>
	#include <linux/fs.h>
	#include <linux/init_syscalls.h>
	#include <linux/stringify.h>
	#include <linux/timekeeping.h>
	#include "initramfs_internal.h"

	struct initramfs_test_cpio {
	char *magic;
	unsigned int ino;
	unsigned int mode;
	unsigned int uid;
	unsigned int gid;
	unsigned int nlink;
	unsigned int mtime;
	unsigned int filesize;
	unsigned int devmajor;
	unsigned int devminor;
	unsigned int rdevmajor;
	unsigned int rdevminor;
	unsigned int namesize;
	unsigned int csum;
	char *fname;
	char *data;
	};

	static size_t fill_cpio(struct initramfs_test_cpio cs, size_t csz, char out)
	{
	int i;
	size_t off = 0;

	for (i = 0; i < csz; i++) {
	char *pos = &out[off];
	struct initramfs_test_cpio *c = &cs[i];
	size_t thislen;

	/* +1 to account for nulterm */
	thislen = sprintf(pos, "%s"
	"%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x%08x"
	"%s",
	c->magic, c->ino, c->mode, c->uid, c->gid, c->nlink,
	c->mtime, c->filesize, c->devmajor, c->devminor,
	c->rdevmajor, c->rdevminor, c->namesize, c->csum,
	c->fname) + 1;
	pr_debug("packing (%zu): %.*s\n", thislen, (int)thislen, pos);
	off += thislen;
	while (off & 3)
	out[off++] = '\0';

	memcpy(&out[off], c->data, c->filesize);
	off += c->filesize;
	while (off & 3)
	out[off++] = '\0';
	}

	return off;
	}

	static void __init initramfs_test_extract(struct kunit *test)
	{
	char err, cpio_srcbuf;
	size_t len;
	struct timespec64 ts_before, ts_after;
	struct kstat st = {};
	struct initramfs_test_cpio c[] = { {
	.magic = "070701",
	.ino = 1,
	.mode = S_IFREG \| 0777,
	.uid = 12,
	.gid = 34,
	.nlink = 1,
	.mtime = 56,
	.filesize = 0,
	.devmajor = 0,
	.devminor = 1,
	.rdevmajor = 0,
	.rdevminor = 0,
	.namesize = sizeof("initramfs_test_extract"),
	.csum = 0,
	.fname = "initramfs_test_extract",
	}, {
	.magic = "070701",
	.ino = 2,
	.mode = S_IFDIR \| 0777,
	.nlink = 1,
	.mtime = 57,
	.devminor = 1,
	.namesize = sizeof("initramfs_test_extract_dir"),
	.fname = "initramfs_test_extract_dir",
	}, {
	.magic = "070701",
	.namesize = sizeof("TRAILER!!!"),
	.fname = "TRAILER!!!",
	} };

	/* +3 to cater for any 4-byte end-alignment */
	cpio_srcbuf = kzalloc(ARRAY_SIZE(c) * (CPIO_HDRLEN + PATH_MAX + 3),
	GFP_KERNEL);
	len = fill_cpio(c, ARRAY_SIZE(c), cpio_srcbuf);

	ktime_get_real_ts64(&ts_before);
	err = unpack_to_rootfs(cpio_srcbuf, len);
	ktime_get_real_ts64(&ts_after);
	if (err) {
	KUNIT_FAIL(test, "unpack failed %s", err);
	goto out;
	}

	KUNIT_EXPECT_EQ(test, init_stat(c[0].fname, &st, 0), 0);
	KUNIT_EXPECT_TRUE(test, S_ISREG(st.mode));
	KUNIT_EXPECT_TRUE(test, uid_eq(st.uid, KUIDT_INIT(c[0].uid)));
	KUNIT_EXPECT_TRUE(test, gid_eq(st.gid, KGIDT_INIT(c[0].gid)));
	KUNIT_EXPECT_EQ(test, st.nlink, 1);
	if (IS_ENABLED(CONFIG_INITRAMFS_PRESERVE_MTIME)) {
	KUNIT_EXPECT_EQ(test, st.mtime.tv_sec, c[0].mtime);
	} else {
	KUNIT_EXPECT_GE(test, st.mtime.tv_sec, ts_before.tv_sec);
	KUNIT_EXPECT_LE(test, st.mtime.tv_sec, ts_after.tv_sec);
	}
	KUNIT_EXPECT_EQ(test, st.blocks, c[0].filesize);

	KUNIT_EXPECT_EQ(test, init_stat(c[1].fname, &st, 0), 0);
	KUNIT_EXPECT_TRUE(test, S_ISDIR(st.mode));
	if (IS_ENABLED(CONFIG_INITRAMFS_PRESERVE_MTIME)) {
	KUNIT_EXPECT_EQ(test, st.mtime.tv_sec, c[1].mtime);
	} else {
	KUNIT_EXPECT_GE(test, st.mtime.tv_sec, ts_before.tv_sec);
	KUNIT_EXPECT_LE(test, st.mtime.tv_sec, ts_after.tv_sec);
	}

	KUNIT_EXPECT_EQ(test, init_unlink(c[0].fname), 0);
	KUNIT_EXPECT_EQ(test, init_rmdir(c[1].fname), 0);
	out:
	kfree(cpio_srcbuf);
	}

	/*
	* Don't terminate filename. Previously, the cpio filename field was passed
	* directly to filp_open(collected, O_CREAT\|..) without nulterm checks. See
	* https://lore.kernel.org/linux-fsdevel/20241030035509.20194-2-ddiss@suse.de
	*/
	static void __init initramfs_test_fname_overrun(struct kunit *test)
	{
	char err, cpio_srcbuf;
	size_t len, suffix_off;
	struct initramfs_test_cpio c[] = { {
	.magic = "070701",
	.ino = 1,
	.mode = S_IFREG \| 0777,
	.uid = 0,
	.gid = 0,
	.nlink = 1,
	.mtime = 1,
	.filesize = 0,
	.devmajor = 0,
	.devminor = 1,
	.rdevmajor = 0,
	.rdevminor = 0,
	.namesize = sizeof("initramfs_test_fname_overrun"),
	.csum = 0,
	.fname = "initramfs_test_fname_overrun",
	} };

	/*
	* poison cpio source buffer, so we can detect overrun. source
	* buffer is used by read_into() when hdr or fname
	* are already available (e.g. no compression).
	*/
	cpio_srcbuf = kmalloc(CPIO_HDRLEN + PATH_MAX + 3, GFP_KERNEL);
	memset(cpio_srcbuf, 'B', CPIO_HDRLEN + PATH_MAX + 3);
	/* limit overrun to avoid crashes / filp_open() ENAMETOOLONG */
	cpio_srcbuf[CPIO_HDRLEN + strlen(c[0].fname) + 20] = '\0';

	len = fill_cpio(c, ARRAY_SIZE(c), cpio_srcbuf);
	/* overwrite trailing fname terminator and padding */
	suffix_off = len - 1;
	while (cpio_srcbuf[suffix_off] == '\0') {
	cpio_srcbuf[suffix_off] = 'P';
	suffix_off--;
	}

	err = unpack_to_rootfs(cpio_srcbuf, len);
	KUNIT_EXPECT_NOT_NULL(test, err);

	kfree(cpio_srcbuf);
	}

	static void __init initramfs_test_data(struct kunit *test)
	{
	char err, cpio_srcbuf;
	size_t len;
	struct file *file;
	struct initramfs_test_cpio c[] = { {
	.magic = "070701",
	.ino = 1,
	.mode = S_IFREG \| 0777,
	.uid = 0,
	.gid = 0,
	.nlink = 1,
	.mtime = 1,
	.filesize = sizeof("ASDF") - 1,
	.devmajor = 0,
	.devminor = 1,
	.rdevmajor = 0,
	.rdevminor = 0,
	.namesize = sizeof("initramfs_test_data"),
	.csum = 0,
	.fname = "initramfs_test_data",
	.data = "ASDF",
	} };

	/* +6 for max name and data 4-byte padding */
	cpio_srcbuf = kmalloc(CPIO_HDRLEN + c[0].namesize + c[0].filesize + 6,
	GFP_KERNEL);

	len = fill_cpio(c, ARRAY_SIZE(c), cpio_srcbuf);

	err = unpack_to_rootfs(cpio_srcbuf, len);
	KUNIT_EXPECT_NULL(test, err);

	file = filp_open(c[0].fname, O_RDONLY, 0);
	if (IS_ERR(file)) {
	KUNIT_FAIL(test, "open failed");
	goto out;
	}

	/* read back file contents into @cpio_srcbuf and confirm match */
	len = kernel_read(file, cpio_srcbuf, c[0].filesize, NULL);
	KUNIT_EXPECT_EQ(test, len, c[0].filesize);
	KUNIT_EXPECT_MEMEQ(test, cpio_srcbuf, c[0].data, len);

	fput(file);
	KUNIT_EXPECT_EQ(test, init_unlink(c[0].fname), 0);
	out:
	kfree(cpio_srcbuf);
	}

	static void __init initramfs_test_csum(struct kunit *test)
	{
	char err, cpio_srcbuf;
	size_t len;
	struct initramfs_test_cpio c[] = { {
	/* 070702 magic indicates a valid csum is present */
	.magic = "070702",
	.ino = 1,
	.mode = S_IFREG \| 0777,
	.nlink = 1,
	.filesize = sizeof("ASDF") - 1,
	.devminor = 1,
	.namesize = sizeof("initramfs_test_csum"),
	.csum = 'A' + 'S' + 'D' + 'F',
	.fname = "initramfs_test_csum",
	.data = "ASDF",
	}, {
	/* mix csum entry above with no-csum entry below */
	.magic = "070701",
	.ino = 2,
	.mode = S_IFREG \| 0777,
	.nlink = 1,
	.filesize = sizeof("ASDF") - 1,
	.devminor = 1,
	.namesize = sizeof("initramfs_test_csum_not_here"),
	/* csum ignored */
	.csum = 5555,
	.fname = "initramfs_test_csum_not_here",
	.data = "ASDF",
	} };

	cpio_srcbuf = kmalloc(8192, GFP_KERNEL);

	len = fill_cpio(c, ARRAY_SIZE(c), cpio_srcbuf);

	err = unpack_to_rootfs(cpio_srcbuf, len);
	KUNIT_EXPECT_NULL(test, err);

	KUNIT_EXPECT_EQ(test, init_unlink(c[0].fname), 0);
	KUNIT_EXPECT_EQ(test, init_unlink(c[1].fname), 0);

	/* mess up the csum and confirm that unpack fails */
	c[0].csum--;
	len = fill_cpio(c, ARRAY_SIZE(c), cpio_srcbuf);

	err = unpack_to_rootfs(cpio_srcbuf, len);
	KUNIT_EXPECT_NOT_NULL(test, err);

	/*
	* file (with content) is still retained in case of bad-csum abort.
	* Perhaps we should change this.
	*/
	KUNIT_EXPECT_EQ(test, init_unlink(c[0].fname), 0);
	KUNIT_EXPECT_EQ(test, init_unlink(c[1].fname), -ENOENT);
	kfree(cpio_srcbuf);
	}

	/*
	* hardlink hashtable may leak when the archive omits a trailer:
	* https://lore.kernel.org/r/20241107002044.16477-10-ddiss@suse.de/
	*/
	static void __init initramfs_test_hardlink(struct kunit *test)
	{
	char err, cpio_srcbuf;
	size_t len;
	struct kstat st0, st1;
	struct initramfs_test_cpio c[] = { {
	.magic = "070701",
	.ino = 1,
	.mode = S_IFREG \| 0777,
	.nlink = 2,
	.devminor = 1,
	.namesize = sizeof("initramfs_test_hardlink"),
	.fname = "initramfs_test_hardlink",
	}, {
	/* hardlink data is present in last archive entry */
	.magic = "070701",
	.ino = 1,
	.mode = S_IFREG \| 0777,
	.nlink = 2,
	.filesize = sizeof("ASDF") - 1,
	.devminor = 1,
	.namesize = sizeof("initramfs_test_hardlink_link"),
	.fname = "initramfs_test_hardlink_link",
	.data = "ASDF",
	} };

	cpio_srcbuf = kmalloc(8192, GFP_KERNEL);

	len = fill_cpio(c, ARRAY_SIZE(c), cpio_srcbuf);

	err = unpack_to_rootfs(cpio_srcbuf, len);
	KUNIT_EXPECT_NULL(test, err);

	KUNIT_EXPECT_EQ(test, init_stat(c[0].fname, &st0, 0), 0);
	KUNIT_EXPECT_EQ(test, init_stat(c[1].fname, &st1, 0), 0);
	KUNIT_EXPECT_EQ(test, st0.ino, st1.ino);
	KUNIT_EXPECT_EQ(test, st0.nlink, 2);
	KUNIT_EXPECT_EQ(test, st1.nlink, 2);

	KUNIT_EXPECT_EQ(test, init_unlink(c[0].fname), 0);
	KUNIT_EXPECT_EQ(test, init_unlink(c[1].fname), 0);

	kfree(cpio_srcbuf);
	}

	#define INITRAMFS_TEST_MANY_LIMIT 1000
	#define INITRAMFS_TEST_MANY_PATH_MAX (sizeof("initramfs_test_many-") \
	+ sizeof(__stringify(INITRAMFS_TEST_MANY_LIMIT)))
	static void __init initramfs_test_many(struct kunit *test)
	{
	char err, cpio_srcbuf, *p;
	size_t len = INITRAMFS_TEST_MANY_LIMIT *
	(CPIO_HDRLEN + INITRAMFS_TEST_MANY_PATH_MAX + 3);
	char thispath[INITRAMFS_TEST_MANY_PATH_MAX];
	int i;

	p = cpio_srcbuf = kmalloc(len, GFP_KERNEL);

	for (i = 0; i < INITRAMFS_TEST_MANY_LIMIT; i++) {
	struct initramfs_test_cpio c = {
	.magic = "070701",
	.ino = i,
	.mode = S_IFREG \| 0777,
	.nlink = 1,
	.devminor = 1,
	.fname = thispath,
	};

	c.namesize = 1 + sprintf(thispath, "initramfs_test_many-%d", i);
	p += fill_cpio(&c, 1, p);
	}

	len = p - cpio_srcbuf;
	err = unpack_to_rootfs(cpio_srcbuf, len);
	KUNIT_EXPECT_NULL(test, err);

	for (i = 0; i < INITRAMFS_TEST_MANY_LIMIT; i++) {
	sprintf(thispath, "initramfs_test_many-%d", i);
	KUNIT_EXPECT_EQ(test, init_unlink(thispath), 0);
	}

	kfree(cpio_srcbuf);
	}

	/*
	* The kunit_case/_suite struct cannot be marked as __initdata as this will be
	* used in debugfs to retrieve results after test has run.
	*/
	static struct kunit_case __refdata initramfs_test_cases[] = {
	KUNIT_CASE(initramfs_test_extract),
	KUNIT_CASE(initramfs_test_fname_overrun),
	KUNIT_CASE(initramfs_test_data),
	KUNIT_CASE(initramfs_test_csum),
	KUNIT_CASE(initramfs_test_hardlink),
	KUNIT_CASE(initramfs_test_many),
	{},
	};

	static struct kunit_suite initramfs_test_suite = {
	.name = "initramfs",
	.test_cases = initramfs_test_cases,
	};
	kunit_test_init_section_suites(&initramfs_test_suite);

	MODULE_DESCRIPTION("Initramfs KUnit test suite");
	MODULE_LICENSE("GPL v2");